The Loch Seaforth ferry is now in drydock, and CalMac have drafted in the Isle of Lewis to cover day runs between Stornoway and Ullapool, while the Hebridean Isles will take care of the overnight freight service.
The Isle of Arran has been drafted in to cover for the Isle of Lewis, which has been on the Castlebay - Oban run in recent months.
A spokesman for CalMac commented: "The Loch Seaforth was specifically designed so that she could do the overnight freight run and the day run, but the Isle of Lewis can’t do this because she cannot carry dangerous goods so we need two boats.
"These alternative arrangements are just for the period of the Loch Seaforth refit. It is an enormously complex situation as not all boats fit all piers, but once the Loch Seaforth returns the vessels will return to where they were beforehand."